title: Coiled-coil fibrous domains mediate ligand binding by macrophage scavenger receptor type II.
abstract: The macrophage scavenger receptor, which has been implicated in the pathogenesis of atherosclerosis, has an unusually broad binding specificity. Ligands include modified low-density lipoprotein and some polyanions (for example, poly(I) but not poly(C]. The scavenger receptor type I (ref. 3) has three principal extracellular domains that could participate in ligand binding: two fibrous coiled-coil domains (alpha-helical coiled-coil domain IV and collagen-like domain V), and the 110-amino-acid cysteine-rich C-terminal domain VI. We have cloned complementary DNAs encoding a second scavenger receptor which we have termed type II. This receptor is identical to the type I receptor, except that the cysteine-rich domain is replaced by a six-residue C terminus. Despite this truncation, the type II receptor mediates endocytosis of chemically modified low-density lipoprotein with high affinity and specificity, similar to that of the type I receptor. Therefore one or both of the extracellular fibrous domains are responsible for the unusual ligand-binding specificity of the receptor.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02168.
authors.forename: L
authors.initials: L
authors.lastname: Rohrer
authors.forename: M
authors.initials: M
authors.lastname: Freeman
authors.forename: T
authors.initials: T
authors.lastname: Kodama
authors.forename: M
authors.initials: M
authors.lastname: Penman
authors.forename: M
authors.initials: M
authors.lastname: Krieger
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004705:Endocytosis; D008077:Lipoproteins, LDL / Q000378:metabolism; D008264:Macrophages / Q000032:analysis*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D000071228:Polyelectrolytes; D011108:Polymers / Q000378:metabolism; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics; D011971:Receptors, Immunologic / Q000378:metabolism*; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D004247:DNA; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D000071228:Polyelectrolytes; D011108:Polymers; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D018110:Receptors, Lipoprotein; D051116:Receptors, Scavenger; D051122:Scavenger Receptors, Class B; C454739:Scarb1 protein, mouse; C032629:acetyl-LDL